How are Master Pages Implemented in 1.4.5?

Aug 12, 2008 at 3:28 AM
<disclaimer:  Haven't started digging through code yet> How are the master pages implemented in 1.4.5?  I found the site.master in the themes folder, but when I copy my own master page down there and rename it site.master, and then modify the default.aspx to use my content place holder tag name it spews saying that it can't find a placeholder called cphBody.  Where all are the placeholder tags distributed / found?